Wireless sensor networks are known for use in commercial vehicles such as intermodal shipping containers, flatbed trucks, corrugated door trailers, etc. One application of such wireless sensor networks is Tire Pressure Monitoring Systems (TPMS) for monitoring the pressure in all the tires of a truck, which helps prevent dangerous tire blowouts and assists in reducing tire wear and improving fuel efficiency. Such systems use pressure sensors that are embedded either on the rim of the wheel or on wall of the tire (direct TPMS) which communicates using short range wireless communication via a gateway to an Electronic Control Unit (ECU) in the vehicle and to a remote server for maintenance/diagnostics etc. at remote location. The system gathers pressure data from all of the wheels in the vehicle and displays the pressure values to the driver, along with a warning if boundary conditions are exceeded.
A typical wireless sensor network comprises multiple sensor modules and one or more gateways. Sensor modules communicate with a gateway via short range RF technologies such as 2.4 GHz Bluetooth Low Energy (BLE), 802.15.4 low-rate wireless communications, ISM band SubGHz 434 MHz, 490 MHz, 868 MHz, 902-928 MHz, etc. Sensor modules are typically battery powered whereas gateways may either be connected to a power source or battery.
In a typical wireless sensor network for use in a vehicle, the sensors may be located in the chassis, spanning both the frame and the wheel hubs. One consideration when implementing such a network is the number of gateways needed for communication with all of the sensors, as well as optimal location of the gateways relative to the sensors. Depending on the mounting position of the gateways, one or more of the sensor modules may not be in line of sight of the gateways, such that the sensors may be unable to communicate reliably with the gateways due to higher path losses and poor sensitivity resulting from small antenna volume.
An aspect of the specification provides a method of dynamically optimizing antenna performance in a wireless sensor network, comprising scanning multiple frequency bands via successive ones of a plurality of antennae for receiving indications of signal strength at each antenna for each scanned frequency band; and selecting one of said plurality of antennae having highest signal strength over one of said multiple frequency bands for communication over said one of said multiple frequency bands.
A further aspect of the specification provides system for dynamically optimizing antenna performance in a wireless sensor network, comprising, a plurality of sensor modules; at least one gateway comprising a plurality of antennae and a transceiver; said transceiver including an RF (radio frequency) front end and a controller configured for selectively connecting said RF front end to said plurality of antennae, said controller configured to: scan multiple frequency bands via successive ones of said plurality of antennae for receiving indications of signal strength at each antenna for each scanned frequency band; and selectively connecting said RF front end to one of said plurality of antennae having highest signal strength over one of said multiple frequency bands for communication over said one of said multiple frequency bands.
A further aspect of the specification provides a gateway for communicating with a plurality of sensor modules via RF (radio frequency) and with a remote server via a cellular network, said gateway comprising a cellular modem; an RF transceiver having a controller and an RF front end; a plurality of antennae; and a controller for selectively connecting said RF front end to said plurality of antennae, said controller configured to: scan multiple frequency bands via successive ones of said plurality of antennae for receiving indications of signal strength at each antenna for each scanned frequency band; and selectively connecting said RF front end to one of said plurality of antennae having highest signal strength over one of said multiple frequency bands for communication over said one of said multiple frequency bands.
Yet another aspect of the specification provides a non-transient computer readable medium containing program instructions for causing a computer to perform a method of dynamically optimizing antenna performance in a wireless sensor network, comprising: scanning multiple frequency bands via successive ones of a plurality of antennae for receiving indications of signal strength at each antenna for each scanned frequency band; and selecting one of said plurality of antennae having highest signal strength over one of said multiple frequency bands for communication over said one of said multiple frequency bands.